This invention relates to an electronic timepiece including an improved time count means for counting reference clock signals of a reference oscillator for each display time unit.
In an electronic timepiece for effecting time display by an electronic type digital display means, an electronic time count means is used to supply electronic time display signals to a display section and a reference oscillator for generating reference clock signals are used to effect time counting by the electronic time count means. That is, the reference oscillator generates a reference clock signal of, for example, 2.sup.15 Hz. The reference clock signal is frequently divided to provide, for example, a one pulse per second (1P/1S) signal. The 1P/1S signal is formed by passing the reference clock signal through a multi-stage frequency divider. Such a 1P/1S second signal is supplied to a decimal counter where carry pulse signals are obtained for every 10 seconds. The 1P/1S (one pulse per 10 seconds) signals are counted at a scale-of-6 second counting circuit from which a time display signal is generated for every 10 seconds. The scale-of-6 second counting circuit generates a carry signal (1P/1M) for each 60 seconds, i.e., each minute. The 1P/1M signal is counted at a minute counting circuit comprising series-connected scale-of-10 and scale-of-6 counters. The `minute` counting circuit generates a time indicating signal corresponding to a minute time unit. The carry signal of the `minute` counting circuit is counted at a scale-of-12 counter to provide a time indicating signal corresponding to a hour time unit.
That is, for each time unit a corresponding scale counter such as a scale-of-6 counter, scale-of-10 counter etc. is provided having a corresponding carry requirement. Each counter is serially connected so that it effects a counting operation by carry signals. Thus providing a time count circuit.
Since such a time count circuit is subjected to digital control, it is formed of series-connected LSI binary counters. The time count circuit is divided into sections according to each time unit and a carry requirement is set for each section according to the time unit. That is, a multi-stage frequency divider is necessary for the reference clock signal of a reference oscillator to be converted to a 1P/1S signal on the basis of which a second coutning is effected. Furthermore, it is also necessary to divide the time count circuit into sections corresponding to time units on the basis of which respective carry requirements are set, requiring a multi-stage arrangement and in consequence resulting in a complicated arrangement. This provides a far to the simplification of the time count circuit. Since the dissipation power of the frequency divider is increased in proporiton to the frequency, the multi-stage arrangement requires a corresponding greater dissipation power. Since a wrist watch etc. are subjected to a restriction on the capacity of a cell, it is necessary to reduce a dissipation power.
It is accordingly the object of this invention to provide a novel electronic timepiece which can make a frequency-division stage sufficiently small and can reduce a dissipation power through the effective use of semiconductor memories without using any conventional time count circuit as a time count means.